• The Journal of the Acoustical Society of Korea
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• 제21권2E호
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• pp.56-62
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• 2002

This paper describes a new method of stability evaluation for an estimated impulse response of a plant. It is difficult for the conventional stability evaluation equation to be used in an adaptive feedforward control system which uses an immeasurable acoustic transfer system of a real plant, because the equation requires an exact true impulse response of the plant. Therefore, the usefulness of the conventional equation is limited in a computer simulation. The proposed method is applicable to not only a computer simulation but also a real feedforward adaptive control system. It is found that the system is stable when the value of misadjustment is below -10 dB through computer simulations and experiments. And also, it is proved that the error signal is stable through the verification using filtered reference and filtered error LMS methods.

• 한국공작기계학회논문집
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• 제12권6호
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• pp.77-83
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• 2003

This paper deals with a position control problem of a hydraulic proportional position control system using a nonlinear friction compensation control. As nonlinear friction, stiction and coulomb friction forces are considered and modeled as deadzone and external disturbance respectively. In order to compensate this nonlinearities, we designed the controller which is the adaptive friction compensator using discrete time Model Reference Adaptive Control method in this paper. Digital Signal Processing board is employed for data acquisition and manipulation. The experimental results show that response is slow and steady-state error cannot be compensated properly without friction compensation but this compensator is effective to obtain fast response and good steady-state response.

• Nuclear Engineering and Technology
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• 제38권3호
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• pp.285-292
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• 2006

Thermoresistant (TR) clones of radiation-induced fibrosarcoma (RIF) cells have been reported to show an adaptive response to 1cGy of low dose radiation, and HSP25 and inducible HSP70 are involved in this process. In this study, to further elucidate the mechanism by which HSP25 and inducible HSP70 regulate the adaptive response, HSP25 or inducible HSP70 overexpressed RIF cells were irradiated with 1cGy and the cell cycle was analyzed. HSP25 or inducible HSP70 overexpressed cells together with TR cells showed increased G1 phase after 1cGy irradiation, while RIF cells did not. $[^3H]-Thymidine$ and BrdU incorporation also indicated that both HSP25 and inducible HSP70 are involved in G1 arrest after 1cGy irradiation. Molecular analysis revealed upregulation of p27Cip/Kip protein in HSP25 and inducible HSP70 overexpressed cells, and cotransfection of p27Cip/Kip antisense abolished the induction of the adaptive response and 1cGy-mediated G1 arrest. The above results indicate that induction of an adaptive response by HSP25 and inducible HSP70 is mediated by upregulation of p27Cip/Kip protein, resulting in low dose radiation-induced G1 arrest.

• 디지털산업정보학회논문지
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• 제10권3호
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• pp.119-125
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• 2014

Echo cancellation is required for a dual-duplex high speed communication such as digital subscriber line(DSL), in order to allow each individual loop to operate in a full duplex fashion. Echo cancellation was one of the most difficult aspects of DSL design, requiring high linearity and total echo return loss in excess of 70 dB. For a long and rapidly changing echo response, if the echo is cancelled by an adaptive echo canceller, the echo canceller needs more taps and its performance is decreased. But if the response is divided into several responses, which response is estimated by a adaptive digital filter and combined, the computation complexities are decreased and the performance is increased. Therefore, the adaptive multi-stage echo canceller is proposed to decrease the computation complexity and increase the performance of echo return loss, in which the echo canceller is composed of several stage echo canceller estimating each divided echo response. Through computer simulations, this multi-stage echo canceller is verified to have merits for high speed communications such as DSL application.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제9권4호
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• pp.431-438
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• 2003

본 연구에서는 문항반응이론식 CAT 기법을 이용하여, 학습부진아를 진단하고 평가 결과를 즉시 확인할 수 있는 학습부진아 진단을 위한 웹기반 적응형 평가시스템을 구현하였다. 적응형 평가시스템은 단순히 피험자에게 검사 문항을 제시하는 것이 아니라, 각 문항의 정보를 계산하여 피험자에게 검사 문항을 제시하고 피험자의 응답을 다음 문항 추출의 입력 조건으로 처리하여 피험자 개개인에게 가장 적합한 문항을 다시 추출하여 피험자에게 제시하는 시스템이다. 이 시스템은 문항의 특성에 관련된 각종 정보들을 문항과 함께 체계적으로 저장하고 관리할 수 있는 평가시스템이다. 그리고 피험자의 반응에 따라 수준을 고려한 문항이 추출되어 피험자의 수준 및 상황에 반응하여 평가의 길이, 난이도가 조절되는 평가시스템이다.

• Clinical and Experimental Pediatrics
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• 제52권6호
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• pp.649-654
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• 2009

The immune system is comprised of cells and molecules whose collective and coordinated response to the introduction of foreign substance is referred to as the immune response. Defense against microbes is mediated by the early reaction (innate immunity) and the late response (adaptive immunity). Innate immunity consists of the epithelial barrier, phagocytes, complement and natural killer cells. Adaptive immunity, a more complex defense reaction, consists of activation of later-developed lymphocytes that, when stimulated by exposure to infectious agents, increase in magnitude and defensive capabilities with each successive exposure. In this review we discuss recent advances in important primary immune deficiency disorders of innate immunity (chronic granulomatous disease, leukocyte adhesion deficiency) and adaptive immunity (severe combined immune deficiency, Wiskott- Aldrich syndrome).

• Journal of Power Electronics
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• 제15권6호
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• pp.1577-1583
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• 2015

In this research, a combined adaptive-robust current controller is developed for non-minimum-phase DC-DC converters in a wide range of operations. In the proposed nonlinear controller, load resistance, input voltage and zero interval of the inductor current are estimated using developed adaptation rules and knowing the operating mode of the converter for the closed-loop control is not required; hence, a single controller can be employed for a wide load and line changes in discontinuous and continuous conduction operations. Using the TMS320F2810 digital signal processor, the experimental response of the proposed controller is presented in different operating points of the buck/boost converter. During transition between different modes of the converter, the developed controller has a better dynamic response compared with previously reported adaptive nonlinear approach. Moreover, output voltage steady-state error is zero in different conditions.

• 대한전자공학회논문지
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• 제27권3호
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• pp.145-155
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• 1990

適應 循環 필터에서 시스템 傳達 函數의 極點이 單位圓 밖으로 나감으로써 시스템이 불안정해지는 것을 방지하기 위해 適應 補償器를 채용한 適應 循環 필터 알고리듬을 제안하였고 제안한 알고리듬이 超安定性을 만족한다는 것을 證明하였다. 제안한 알고리듬 適應 雜音 除去器에 응용하여 LS방법의 適應 循環 필터를 이용한 適應 雜音 除去器, 適應 非循環 필터를 이용한 適應 雜音 除去器와의 성능을 比較하여 제안한 알고리듬의 妥當性을 立證하였다.

• 전기학회논문지
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• 제60권2호
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• pp.423-430
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• 2011

In adaptive filtering, the sparseness of impulse response and input signal characteristics are very important factors of it's performance. This paper presents a subband improved proportionate normalized least square (SIPNLMS) algorithm which combines IPNLMS for impulse response sparseness and subband filtering for prewhitening the input signal. As drawing and combining the advantage of conventional approaches, the proposed algorithm, for impulse responses exhibiting high sparseness, achieve improved convergence speed and tracking ability. Simulation results, using colored signal(AR(4)) and speech input signals, show improved performance compared to fullband structure of existing methods.

• The Journal of the Acoustical Society of Korea
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• 제17권2E호
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• pp.3-9
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• 1998

Since the introduction of hands-free phone set and teleconferencing system, acoustic echo cancellation has been a challenge for engineers. Recently many researches have shown that the best solution for the acoustic echo compensation problem is represented by an adaptive filter which iteratively tries to identify the unknown impulse response of the system from loudspeaker to microphone. In this paper, we apply the delayless subband adaptive filters and fast affine projection algorithm for the identification of room impulse response. Simulation results show 3∼8 dB more enhanced performance than conventional fullband adaptive filters or subband adaptive filters. In addition, fast affine projection algorithm shows better convergence speed at the expense of the low computational complexity than conventional LMS algorithm.